1. Field of the Invention
The present invention relates to a ceramic heater and more particularly to a heating element of sintered bodies, and a conformation of the heating element and covering substrates.
2. Description of the Prior Art
Conventionally, nickel-chromium alloy has been widely used as a heating element for heating or ignition use. Non-metallic heating elements composed of such materials as silicon carbide, zirconia, molybdenum silicide, lanthanum chromite, and carbon are also commercially available.
As nickel-chromium alloy is easily oxidized, the heating element composed of the alloy is used under limited conditions. Also the element when used in a relatively good condition may decrease gradually in cross sectional area by oxidation.
This, in turn, will give rise to severe local heating, which may result in self burn-out of the element.
Non-metalic materials described above are not so widely used as is nickel-chromium alloy because of their low oxidation resistance or high fabrication cost.